1. Field of the Invention
This invention relates to a toner cartridge assembled with a developing device of electrostatic copying apparatus, facsimile systems, etc., which uses a magnetic toner.
2. Description of the Prior Art
Unlike a two-component developer comprising a mixture of a nonmagnetic toner particle and a ferromagnetic carrier particle, a single component magnetic toner offers advantages in that the developer has only to be replenished during use because it is merely used up and the need to effect carrier replacements due to the fatigue of the carrier is eliminated, and that the need to obtain a mixture of toner particles and carrier particles suitable for producing a uniform toner concentration necessary for achieving frictional charging of the toner particles and carrier particles is eliminated. In view of these advantages, there has in recent years been a tendency to use a single component magnetic toner in place of a two-component developer for developing an electrostatic latent image into a visible toner image in electrostatic copying apparatus, facsimile systems, printers, etc.
FIG. 1 shows one example of developing device using a magnetic toner. As shown, the developing device includes a hopper 1 for a magnetic toner 2, a lid 3 for the hopper 1, and a magnet roll 4 having a magnet 7 secured to a shaft 6 and housed in a nonmagnetic sleeve 5. In operation, the magnet 7 and the nonmagnetic sleeve 6 are rotated relative to each other. For example, the nonmagnetic sleeve 5 is rotated in the direction of an arrow and the magnetic toner 2 is drawn off an outlet 8 and caused to flow in the direction of the arrow over the sleeve 5 to form a magnetic brush which rubs against the surface of a photosensitive member 9 to develop an electrostatic latent image formed thereon into a toner image. When the magnetic toner 2 is supplied to the hopper 1, the lid 3 is manually opened and the magnetic toner is poured into the hopper 1. This operation is troublesome and time consuming because it is necessary to be careful not to spill the toner from the hopper deep into lower parts of the apparatus and to supply the toner in an amount which is more or less uniform for each operation.
Proposals have hitherto been made to use various types of toner cartridges for performing toner supply in one operation without any trouble, as disclosed in Japanese Utility Model Application Laid-Open Number 1246/80, Japanese Patent Application Laid-Open Number 48660/81 and Japanese Patent Application Laid-Open Number 52779/81, for example. Toner cartridges of the prior art have suffered the disadvantages that they are relatively complex in construction and high in cost, and that the structure for receiving the cartridge fitted therein is also complex in construction.